Wrap-On Reactive Element Barrier Packer and Method of Creating Same

ABSTRACT

Systems and methods for installing an elastomeric element onto a packer mandrel or other existing oil field tubular equipment. In particular aspects, the packer device has a swellable elastomeric packer element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority of U.S. Provisional PatentApplication Ser. No. 60/933,471 filed Jun. 6, 2007.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to packer devices. In particular aspects, theinvention provides devices and methods for securing a packer element toa packer mandrel.

2. Description of the Related Art

Packers are used to create a fluid seal within a wellbore between a toolstring and the wellbore wall. Packer devices incorporate elastomericsealing elements that surround a central mandrel. Particular variationsof these packers are those that employ elements that respond to thesurrounding well fluids and swell to form a seal. The packer device isincorporated into a wellbore toolstring and disposed into the wellbore.When the packer is to be set, the packer element is extruded or expandedradially, as is known in the art, to contact and form a seal against thewellbore wall.

In certain situations, there are problems with timely delivery and costassociated with conventional packer elements because of the limitednumber of manufacturers capable of making the parts and delaysassociated with material procurement and processes required tomanufacture the conventional packers. One way of mitigatingmanufacturing lead time and costs is to create vulcanized or curedrubber sleeves that can be slid over a mandrel, which, in this case,could be any existing oilfield tubular equipment, and adhered directly.The inner diameter of the cured sleeve is sized to form to the outerdiameter of the mandrel, and with a cured sleeve of the rubber element,the strength of the rubber requires the assistance of machinery to allowthe sleeve of rubber to be slid over the end of the mandrel to thedesired position. The inventor has observed that a packer sealing orbarrier element formed of an elastomer that expands or swells uponcontact with wellbore fluids can be adhered directly to a mandrel orother existing oil field tubular equipment without the use of assistingmachinery by wrapping a helically-cut, cured sleeve of rubber around thedesired position of the mandrel. If the element is merely slipped ontothe mandrel from an end, in the manner of a continuous cylindricalsleeve, any adhesive can be wiped off, possible resulting in a poor bondof the packer element to the mandrel. Wrapping a helically cut sleeveover the area prepared with adhesive would eliminate the wiping effectcreated by a solid sleeve in addition to eliminating the need forassisting machinery.

SUMMARY OF THE INVENTION

The invention provides systems and methods for installing an elastomericelement onto a packer mandrel or other existing oil field tubularequipment. In particular aspects, the invention relates to the assemblyof a packer device having a swellable elastomeric packer element.

BRIEF DESCRIPTION OF THE DRAWINGS

The structure and operation of the invention will be more readilyunderstood with reference to the following drawings, which areillustrative thereof and among which like components are numbered withlike reference numerals:

FIG. 1 illustrates an exemplary curing mandrel having elastomericmaterial applied to it.

FIG. 2 depicts removal of cured elastomer from the curing mandrel.

FIG. 3 illustrates the operation of applying the cured elastomer to apacker mandrel.

FIG. 4 illustrates an exemplary operation for disposing an uncuredelastomer upon a packer mandrel.

FIG. 5 depicts an exemplary technique for curing uncured elastomer uponthe packer mandrel using curing wraps.

FIG. 6 depicts that arrangement shown in FIG. 5 now with an exemplaryheating source applied.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In accordance with an embodiment of the present invention, uncuredelastomer 10 is disposed onto a generally cylindrical curing mandrel 12of desired size, as illustrated in FIG. 1. These rubbers or elastomersare of the type that will swell in response to contact with fluids ofthe type found within a wellbore. No bonding material is used betweenthe curing mandrel 12 and the elastomer 10. The elastomer 10 is thencured in place on the curing mandrel 12 in a manner known in the art.Upon completion of curing, the cured elastomer 10 is then removed fromthe curing mandrel 12. In a preferred embodiment, the cured elastomer 10is removed by first cutting through the elastomer 10. It is furtherpreferred that the cuts 14 form a spiral or helical pattern so that thecured elastomer that is to be removed is in a substantially helicalpattern. The elastomer 10 is then unwrapped from the curing mandrel 12as indicated by the arrow 16 in FIG. 2.

The cured elastomer 10 is then applied and secured to the outer radialsurface of a generally cylindrical packer mandrel or other tubularoilfield equipment 18, as depicted in FIG. 3. It is noted that thepacker mandrel 18 preferably has the same or similar diameter to that ofthe curing mandrel 12 so that the elastomer 10 can be wrapped onto thepacker mandrel 18, as in the direction depicted by arrow 19 in FIG. 3,and form a complete and substantially intact cylinder withoutdiscontinuities. Preferably, a bonding agent is used to help bond theelastomer 10 to the packer mandrel 18. In a currently preferredembodiment, the bonding agent comprises a suitable epoxy. A heatedliquid elastomer is preferably also applied to the seams correspondingto the cuts 14 previously made in the elastomer 10 to adhere thecuts/seams 14 together and integrate the elastomer 10. The elastomer 10is preferably then retained in place upon the packer mandrel 18 usingclamps or similar means while the bonding agent sets and dries. Once thebonding agent has adequately set and cured, the completed packer devicecan be run into a wellbore in a manner that is known in the art.

It is preferred to use the system and method of the present inventionwith elastomers that are reactive or swell in response to wellborefluids. With packers that incorporate such reactive or swellableelastomer, it is desired to have the packer element 10 secured to thepacker mandrel 18 along substantially the entire axial length of thepacker element 10 and about the entire circumference of the interfacebetween the packer mandrel 18 and the packer element 10. A barrierpacker 20 is created that is reactive to fluids within the wellbore.

In a variation of the system and method of the invention, the elastomer10 is put on a rubber mill and cut into long strips or extruded into anuncured cylindrical pre-form 15 using a rubber extruder andappropriately formed extruder die, as is known in the art. A curingmandrel 12 is not needed for the application of uncured rubber. For thecase of uncured strips of rubber, the elastomer 10 is wrapped around thedesired area of the packer mandrel 18, already prepared with anappropriate bonding agent in the manner described for the mandrel 18below. For the case of an uncured, extruded cylindrical pre-form 15, theuncured pre-form 15 is placed onto the surface of the packer mandrel 18,as depicted in FIG. 4. It is noted that the mandrel 18 has already beenprepared with an appropriate bonding agent in the same manner as for theuncured rubber strips. For the case of the extruded cylindrical pre-form15, the interior diameter 20 of the pre-form would be adequately largeenough to permit the pre-form 15 to easily slide over the pipe mandrel18 to the approximate location prepared with the bonding agent withoutwiping the bonding agent from the surface of the mandrel 18.

Curing is then conducted upon the assembled packer assembly 22. Onecurrently preferred method of curing the elastomer 15, as illustrated inFIG. 5, is to wrap curing wraps 26 around the uncured elastomer 15.Curing wraps 26 are usually a film or tape, typically fashioned fromnylon, with a significant shrinkage of approximately 7% to 11% thatoccurs during the curing process. The curing wraps 26 may be wrappedover the uncured elastomer 15 in an overlapping spiral pattern known tothose familiar with rubber wrapping processes, although other suitablewrapping patterns may be used. During curing of the elastomer 15, thecuring wraps 26 shrink, which applies a significant radially-inwardcompressive load to the elastomer 15 that is curing underneath. Aheating source, such as a band heater 28, of a type known in the art, isthen disposed over the curing wraps 26. FIG. 6 illustrates the packerdevice 22 now disposed within an annular band heater 28 to cause theelastomer 15 to be cured by applied heat. The band heater 28 isactivated by a power source 30 to cure the elastomer 15. As the uncuredelastomer 15 heats up during the cure cycle, any spaces or voids willknit together and close from the vulcanization. The bonding agent willactivate and begin bonding the curing elastomer 15 to the mandrel 18.The length of the curing cycle will be determined by the thickness ofthe elastomer 15 being cured. Generally, the curing process requiresthat the elastomer be maintained at a temperature of about 300° to about320° F. for around 1.5 hours. Heat may alternatively be applied by anyof a number of known heating sources, including, for example, heatingblankets similar to those used for annealing welds on large pieces, asis known in the art. Alternatively, the elastomer 10 may be cured usinga specialized mobile molding unit, of a type know to those of skill inthe art. Where a mobile molding unit is used for the curing lo process,curing wraps 26 are not necessary to the curing process.

In a related aspect, the invention contemplates preparation of thepacker mandrel 18 prior to affixing the elastomer 10 thereto. The packermandrel 18 is preferably prepared by sandblasting, grinding, or buffingwith sand paper or a similar abrasive material to remove rust and scalefrom the outer radial surface of the packer mandrel 18. It is thencleaned with a solvent to remove oils and other chemicals. Then, aprimer and bonding agent for uncured rubber or an epoxy for the curedrubber is applied to the area. Finally, the elastomer 10 is wrapped overthe mandrel 18 prior to curing. In the case of a cured piece of rubber,the rubber is wrapped over the epoxy.

Those of skill in the art will recognize that numerous modifications andchanges may be made to the exemplary designs and embodiments describedherein and that the invention is limited only by the claims that followand any equivalents thereof.

1. A method of forming a packer for a wellbore comprising the steps of:disposing an uncured elastomer onto a curing mandrel, the elastomerbeing swellable in response to contact with wellbore fluids; curing theswellable elastomer; removing the cured swellable elastomer from thecuring mandrel; wrapping the cured swellable elastomer onto a generallycylindrical packer mandrel.
 2. The method of claim 1 further comprisingthe step of securing the swellable elastomer to the packer mandrel witha bonding agent.
 3. The method of claim 1 wherein the cured swellableelastomer is wrapped onto the packer mandrel in a substantially helicalpattern.
 4. The method of claim 1 wherein the step of removing theremoving the cured swellable elastomer from the curing mandrelcomprises: cutting through the cured elastomer in a substantiallyhelical pattern; and unwrapping the cut cured elastomer from the curingmandrel.
 5. The method of claim 2 further comprising the step ofretaining the cured elastomeric material upon the packer mandrel with aclamp and allowing the bonding agent to set.
 6. The method of claim 2wherein the bonding agent comprises epoxy.
 7. The method of claim 2wherein the bonding agent comprises molten elastomer.
 8. A method ofassembling a packer device comprising: disposing a section of uncuredelastomer upon a packer mandrel, the elastomer being swellable inresponse to wellbore fluids; and curing the elastomer.
 9. The method ofclaim 8 wherein the step of curing the elastomer comprises wrapping theuncured elastomer with curing wraps.
 10. The method of claim 8 whereinthe step of curing the elastomer comprises applying heat to the uncuredelastomer from a heat source.
 11. The method of claim 10 wherein theheat source comprises a band heater.
 12. The method of claim 8 furthercomprising the step of securing the elastomer to the packer mandrel witha bonding agent.
 13. The method of claim 10 wherein the heat source is amobile molding unit.
 14. A packer device comprising: a generallycylindrical packer mandrel; and a cured strip of swellable elastomerdeposited onto the packer mandrel by wrapping.
 15. The packer device ofclaim 14 wherein the swellable elastomer is secured in place upon thepacker mandrel by a bonding agent.
 16. The packer device of claim 15wherein the bonding agent comprises epoxy.
 17. The packer device ofclaim 15 wherein the bonding agent comprises elastomer.
 18. The packerdevice of claim 14 wherein the cured strip of elastomer is wrapped ontothe packer mandrel in a generally helical pattern.